公开了一种制备聚酯的方法,其特征在于包括下述步骤:a)将聚对苯二甲酸乙二醇酯废料悬浮在含有酯交换催化剂的乙二醇和/或1,2‑丙二醇中,b)加热步骤a)中获得的反应混合物以解聚聚对苯二甲酸乙二醇酯废料足以将聚对苯二甲酸乙二醇酯分解为单体和低聚物的时间,c)加入下述形式的形成端基的单体:聚亚烷基二醇单烷基醚、脂肪醇、脂肪胺、脂肪酸或其酯或它们中两种或更多种的混合物、和/或磺基(聚)亚烷基二醇和/或磺芳基羧酸或其酯,d)加入磺基亚芳基二羧酸或其形成聚酯的衍生物,e)任选地,加入脂族二醇、脂环族二醇、有机二羧酸、它们的形成聚酯的衍生物、交联剂、或它们中两种或更多种的混合物,和f)加热反应混合物,同时蒸馏掉乙二醇、任选的1,2‑丙二醇和反应混合物中存在的或通过酯交换和缩聚形成的另外的化合物,条件是所述反应混合物的温度不超过250℃。该方法能够由聚酯废料制备具有所选择端基的聚对苯二甲酸乙二醇酯或丙二醇酯。工艺产物的特征在于良好的去污性能并可用作洗涤剂和清洁剂中的添加剂。
Disclosed is a process for the preparation of polyesters, comprising the following steps and characterized by the following measures:a) suspending polyethylene terephthalate waste in ethylene glycol and/or in 1,2-propylene glycol containing a transesterification catalyst,b) heating the reaction mixture to depolymerize the polyethylene terephthalate waste for a time sufficient to decompose the polyethylene terephthalate into monomers and into oligomers,c) addition of end group forming monomers in the form of polyalkylene glycol monoalkyl ethers, fatty alcohols, fatty amines, fatty acids or esters thereof or mixtures of two or more thereof, and/or sulfo(poly)alkylene glycols and/or sulfoaryl carboxylic acids or esters thereof,d) addition of sulfoarylene dicarboxylic acids or polyester-forming derivatives thereof,e) optionally adding aliphatic diols, cycloaliphatic diols, organic dicarboxylic acids, their polyester-forming derivatives, crosslinkers or mixtures of two or more thereof,f) heating the reaction mixture while distilling off ethylene glycol, optionally 1,2-propylene glycol and further compounds present in the reaction mixture or formed by transesterification and polycondensation, with the proviso that the temperature of the reaction mixture does not exceed 250° C.This process enables the production of polyethylene or polypropylene terephthalates with selected end groups from polyester waste. The process products are characterized by good soil release properties and can be used as additives in detergents and cleaning agents.